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Inorg. Chem. 1998, 37, 6002-6006
Theoretical Evidence for Transannular Metal-Metal Interactions in Dinuclear Coinage Metal Complexes† Eduardo J. Ferna´ ndez, Jose´ M. Lo´ pez-de-Luzuriaga, Miguel Monge, and Miguel A. Rodrı´guez* Departamento de Quı´mica, Universidad de La Rioja, E-26001 Logron˜o, Spain
Olga Crespo, M. Concepcio´ n Gimeno, and Antonio Laguna* Departamento de Quı´mica Inorga´nica, Instituto de Ciencia de Materiales de Arago´n, Universidad de Zaragoza-CSIC, E-50009 Zaragoza, Spain
Peter G. Jones Institut fu¨r Anorganische und Analytische Chemie der Technischen Universita¨t, Postfach 3329, D-38023 Braunschweig, Germany ReceiVed July 7, 1998 The dinuclear head-to-tail complexes [M2(PPh2CH2SPh)2]2+ (M ) Cu (1), Ag (2a, 2b), Au (4)) are obtained either by reaction of [Cu(CH3CN)4]CF3SO3, AgClO4, AgCF3SO3, with equimolecular amounts of PPh2CH2SPh or of [AuCl(PPh2CH2SPh)] (3), prepared by reaction of [AuCl(tht)] and PPh2CH2SPh, with AgCF3SO3. The crystal structures of complexes 2a and 4 have been established by X-ray diffraction studies. Ab initio HF/II and MP2/II calculations have been performed on the [M2(H2PCH2SH)2]2+ model, indicating that metallophilic attraction is indeed present for all the coinage metals as a correlation effect and is strengthened in the case of gold by relativistic effects. Since experimental and theoretically predicted geometries are in close agreement, we assume that our calculations are accurate enough to obtain valid conclusions.
Introduction Despite the fact that two closed-shell metal cations would normally be expected to repel each other, a large number of inorganic and organometallic compounds have been described whose structures indicate strong metal-metal attractions.1 Particular evidence has now been accumulated for an attractive interaction between two d10 ions. Ab initio calculations indicate the attraction as a correlation effect but strengthened by the large relativistic effects for heavy elements, especially in the case of Au(I).2 Apart from its fundamental interest, this aurophilic attraction3 may play a role in the medical applications of gold compounds4 or be associated with useful optical properties.5 In contrast, the analogous cuprophilicity and argentophilicity of the lighter congeners is still a matter of controversy. Thus, the † Dedicated to Professor Pascual Royo on the occasion of his 60th birthday. * Corresponding author. Tel.: 34-976-761185. Fax: 34-976-761187. E-mail:
[email protected]. (1) Pyykko¨, P. Chem. ReV. 1997, 97, 597. (2) Pyykko¨, P. Chem. ReV. 1988, 88, 563. Pyykko¨, P.; Zhao, Y. Angew. Chem., Int. Ed. Engl. 1991, 30, 604. (3) Schmidbaur, H. Gold Bull. 1990, 23, 11; Interdis. Sci. ReV. 1992, 7, 213; Pure Appl. Chem. 1993, 65, 691; Chem. Soc. ReV. 1995, 391. (4) Sadler, P. J.; Sue, R. E. Metal-Based Drugs 1994, 1, 107. (5) Wang, S.; Garzo´n, G.; King, C.; Wang, J.-C.; Fackler, J. P., Jr. Inorg. Chem. 1989, 28, 4623. Narayanaswamy, R.; Young, M. A.; Parkhurst, E.; Ouellette, M.; Kerr, M. E.; Ho, D. M.; Elder, R. C.; Bruce, A. E.; Bruce, M. R. M. Inorg. Chem. 1993, 32, 2506. Tang, S. S.; Chang C.-P.; Lin, I. J. B.; Liou, L.-S.; Wang, J.-C. Inorg. Chem. 1997, 36, 2294.
short metal-metal distances observed for copper and silver dinuclear complexes have been attributed to the ligand architecture.6 Furthermore, the existence of a copper-copper bonding interaction to reflect the short contacts has both been supported7 and refuted8 at various levels of theory. To compare the metallophilicity of the three coinage metals, a set of complexes is required involving the same ligands, the same coordination number and geometry.9 There are few examples that would permit a clean comparison of Cu‚‚‚Cu, Ag‚‚‚Ag, and Au‚‚‚Au metallophilic bonding.1 We report here the first comparative study of the transannular MI‚‚‚MI attraction for the three coinage metals. In the course of our work on dinuclear complexes [M2L2]2+,10 we decided to concentrate on P-S donor bidentate ligands, at least in part because the majority of coinage metal compounds used in modern technology and medicine or present in biological systems are based on phosphorus and/or sulfur donor ligands.11-15 Thus we chose the potentially bidentate ligand PPh2CH2SPh (6) Cotton, F. A.; Feng, X.; Makusz, M.; Poli, R. J. Am. Chem. Soc. 1988, 110, 7077. (7) Merz, K. M., Jr.; Hoffmann, R. Inorg. Chem. 1988, 27, 2120. Mehrotra, P. K.; Hoffmann, R. Inorg. Chem. 1978, 17, 2187. (8) Ko¨lmel, C.; Ahlrichs, R. J. Phys. Chem. 1990, 94, 5536. Scha¨fer, A.; Huber, C.; Gauss, J.; Ahlrichs, R. Theor. Chim. Acta 1993, 87, 29. (9) Bayler, A.; Schier, A.; Bowmaker, G. A.; Schmidbaur, H. J. Am. Chem. Soc. 1996, 118, 7006. Tripathi, U. M.; Bauer, A.; Schmidbaur, H. J. Chem. Soc., Dalton Trans. 1997, 2865. (10) Ferna´ndez, E. J.; Gimeno, M. C.; Jones, P. J.; Laguna, A.; Laguna, M.; Lo´pez-de-Luzuriaga, J. M.; Rodrı´guez, M. A. Chem. Ber. 1995, 128, 121.
10.1021/ic980786q CCC: $15.00 © 1998 American Chemical Society Published on Web 10/28/1998
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and employed it in copper, silver or gold systems in order to compare the metal-metal interactions in the resulting complexes. Results and Discussion Synthesis. We have synthesized the head-to-tail complexes [M2(PPh2CH2SPh)2]X2 (M ) Cu, X ) CF3SO3 (1); M ) Ag, X ) ClO4 (2a), CF3SO3 (2b); M ) Au, X ) CF3SO3 (4)) by reaction of equimolecular amounts of the phosphinothioether ligand and the appropriate metallic precursor for Cu and Ag (eq 1).
(1) Figure 1. Structure of the cation of complex 4 in the crystal. Displacement parameter ellipsoids represent 50% probability surfaces. H atoms are omitted for clarity. Table 1. Selected Bond Lengths (Å) and Angles (deg) for 4a
In case of the gold derivative a typical reaction between the gold precursor [Au(tht)2]CF3SO3 (tht ) tetrahydrothiophene) and the phosphinothioether ligand in molar ratio 1:1 does not produce the expected product; only one tht ligand is substituted. This result differs from those previously described with diphosphines and even with a similar phosphine with three thioether functions.16 An alternative pathway consists of the reaction of [AuCl(PPh2CH2SPh)] (3) (see Experimental Section) and AgCF3SO3 in equimolecular amounts to give [Au(PPh2CH2SPh)]CF3SO3 “in situ”, which dimerizes to the desired product in the crystallization process (eq 2). The analytical data and physical and spectroscopic properties of complexes 1-4 are as expected.
(2)
Crystal Structures. The crystal structure of [Au2(PPh2CH2SPh)2](CF3SO3)2 (4) has been confirmed by X-ray diffraction studies and is shown in Figure 1. A selection of bond lengths and angles are collected in Table 1. The molecule has imposed crystallographic inversion symmetry and thus only half of it represents the asymmetric unit. Each gold atom is bonded to one sulfur and one phosphorus atom of the two different PPh2(11) Rapson, W. S.; Groenewald, T. Gold Usage; Academic Press: London, 1978. (12) Sadler, P. J. Gold Bull. 1976, 9, 110. (13) (a) Abstracts, Second International Conference on Gold and Silver in Medicine. J. Inorg. Biochem. 1991, 42, 289. (b) Dash, K. C.; Schmidbaur, H. In Metal Ions in Biological Systems; Sigel, H., Ed.; Marcel Dekker: New York, 1982; p 179. (14) Peisach, J.; Aisen, P.; Blumberg, W. E. The Biochemistry of Copper; Academic Press: New York, 1996. (15) Karlin, K. D.; Zubieta, J. Biological and Inorganic Copper Chemistry; Adenine Press: Guiderland, NY, 1986. (16) Fuchs, S.; Lo´pez-de-Luzuriaga, J. M.; Olmos, M. E.; Sladek, A.; Schmidbaur H. Z. Naturforsch. 1997, 52B, 217.
Au-P Au-Au#1 P-C(21) S(1)-C(31) P-Au-S(1)#1 S(1)#1-Au-Au#1 C(11)-P-C(1) C(11)-P-Au C(1)-P-Au C(31)-S(1)-Au#1 S(1)-C(1)-P
2.2721(11) 2.9020(5) 1.814(4) 1.783(5) 175.07(4) 93.45(3) 107.8(2) 113.77(14) 112.57(14) 107.26(14) 116.9(2)
Au-S(1)#1 P-C(11) P-C(1) S(1)-C(1) P-Au-Au#1 C(11)-P-C(21) C(21)-P-C(1) C(21)-P-Au C(31)-S(1)-C(1) C(1)-S(1)-Au#1
2.3619(11) 1.808(4) 1.831(4) 1.807(4) 91.36(3) 106.8(2) 104.8(2) 110.50(14) 103.7(2) 107.64(14)
a Symmetry transformations used to generate equivalent atoms: #1, -x + 1, -y + 1, -z.
CH2SPh ligands giving the head-to-tail isomer. The Au-P distance is 2.2721(11) Å and is very similar to those found in other dinuclear gold complexes with mixed sulfur-phosphorus ligands such as [Au2(µ-S(CH2)3S)(µ-dppm)] (2.259(3) and 2.266(3)17 Å) (dppm ) bis(diphenylphosphino)methane) or [Au2(µ-SCH2PEt2)2] (2.27 Å).18 However, the Au-S(1i) (i ) -x + 1, -y + 1, -z) distance of 2.3619(11) Å is slightly longer than in the complexes mentioned above, perhaps because the uncharged sulfur donor in 4 leads to weaker Au-S bonds. The Au‚‚‚Au distance is 2.9020(5) Å, a typical value for gold-gold interactions in dinuclear gold(I) complexes. There is a weak contact from gold to an oxygen atom of the triflate ligand: Au‚‚‚O(2), 3.093(4) Å. The crystal structure of the silver complex in the perchlorate salt (complex 2a) has been confirmed by X-ray diffraction studies. The complex crystallizes with two independent molecules, each one associated with a symmetry center; the asymmetric unit thus consists of two-half molecules. One of the molecules is shown in Figure 2 and a selection of bond lengths and angles in Table 2. Each silver atom is bonded to one sulfur and one phosphorus atom of the different PPh2CH2SPh ligands giving (as in the gold compound) the head-to-tail isomer. The two independent silver atoms have a slightly distorted linear geometry, with angles P(1)-Ag(1)-S(1), 172.83(4),° and P(2)-Ag(2)-S(2), 173.97(4)°. This distortion may arise from weak Ag‚‚‚O contacts with the perchlorate (17) Da´vila, R. M.; Elduque, A.; Grant, T.; Staples, R. J.; Fackler, J. P., Jr. Inorg. Chem. 1993, 32, 1749. (18) Crane, W. S.; Beall, H. Inorg. Chim. Acta 1978, 31, L469.
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Figure 2. Perspective view of the cation of one of the molecules of complex 2a. Displacement parameter ellipsoids represent 50% probability surfaces. H atoms are omitted for clarity.
Figure 3. Structure of complex 2a in the crystal. H atoms are omitted for clarity. There are no further contacts from the depicted perchlorates to other silver atoms.
Table 2. Selected Bond Lengths (Å) and Angles (deg) for 2aa
study necessitates the use of [M2(H2PCH2SH)2]2+ as a model for the ab initio calculations. Any effect of the weak M‚‚‚O contacts, which we assume to be minimal, is neglected. All calculations were carried out using the Gaussian94 program package.21 The molecular geometries were initially optimized, within appropriate molecular symmetry constraints (Ci), at the Hartree-Fock self-consistent field (HF) level of theory, and electron correlation, keeping the core orbitals frozen, was included in further optimizations by using Møller-Plesset perturbation theory22 with second-order corrections (MP2) employing Schlegel’s analytical gradient procedure.23 The following basis set combination was employed. For C, S, P, and H, the standard split-valence 6-31G(d) basis set,24,25 and for Cu, Ag and Au, the pseudorelativistic Hay-Wadt smallcore effective core potential,26 where the minimal basis set has been split to [341/2111/41], [341/3111/31], and [341/3111/21], respectively.27 This basis set combination will be hereafter referred to as II. The HF/II and MP2/II levels of theory have demonstrated their ability to calculate optimized geometries of transition metal complexes with good accuracy.28 The absolute energies and the most relevant geometrical parameters of the [CH2(SHMPH2)2CH2]2+ optimized structures with the HF/II wave function are given in Figure 2. Several features are noteworthy. At this level of theory, the M-M
Ag(1)-P(1) Ag(1)-Ag(1)#1 P(1)-C(21) S(1)-C(1) Ag(2)-P(2) Ag(2)-Ag(2)#2 P(2)-C(51) S(2)-C(31) P(1)-Ag(1)-S(1) S(1)-Ag(1)-Ag(1)#1 C(11)-P(1)-C(10) C(11)-P(1)-Ag(1) C(10)-P(1)-Ag(1) C(1)-S(1)-Ag(1) P(2)-Ag(2)-S(2) S(2)-Ag(2)-Ag(2)#2 C(41)-P(2)-C(40) C(41)-P(2)-Ag(2) C(40)-P(2)-Ag(2) C(31)-S(2)-Ag(2)
2.3896(12) 2.9501(8) 1.824(4) 1.781(5) 2.3931(13) 2.9732(9) 1.821(4) 1.790(4) 172.83(4) 96.58(3) 107.9(2) 111.01(14) 117.68(14) 107.1(2) 173.97(4) 96.02(3) 107.7(2) 113.7(2) 117.7(2) 111.3(2)
Ag(1)-S(1) P(1)-C(11) P(1)-C(10) S(1)-C(10)#1 Ag(2)-S(2) P(2)-C(41) P(2)-C(40) S(2)-C(40)#2
2.4406(12) 1.807(4) 1.831(4) 1.807(4) 2.4519(13) 1.805(5) 1.838(4) 1.809(4)
P(1)-Ag(1)-Ag(1)#1 C(11)-P(1)-C(21) C(21)-P(1)-C(10) C(21)-P(1)-Ag(1) C(1)-S(1)-C(10)#1 C(10)#1-S(1)-Ag(1) P(2)-Ag(2)-Ag(2)#2 C(41)-P(2)-C(51) C(51)-P(2)-C(40) C(51)-P(2)-Ag(2) C(31)-S(2)-C(40)#2 C(40)#2-S(2)-Ag(2)
86.37(3) 105.1(2) 100.2(2) 113.8(2) 103.8(2) 109.23(14) 86.75(3) 106.2(2) 100.7(2) 109.4(2) 103.3(2) 105.9(2)
a Symmetry transformations used to generate equivalent atoms: #1, -x + 1, -y, -z + 1; #2, -x + 2, -y, -z + 1.
anion: Ag(2)‚‚‚O(7), 2.640(3) Å; Ag(1)‚‚‚O(5), 2.851(5) Å; and Ag1‚‚‚O3, 2.988(4) Å (see Figure 3). The Ag-P distances are 2.3895(12) and 2.3932(13) Å, and the Ag-S bond lengths are 2.4406(12) and 2.4519(13) Å; these values are similar to those obtained in the complex [Ag{PPh2(CH2)2SEt}]ClO4.19 It is noteworthy to mention that both Ag-P and Ag-S distances are longer than the corresponding Au-P and Au-S distances, thus corroborating the observations made by Schmidbaur that the covalent radius of gold(I) is smaller than that of silver(I).9 Both dimers display Ag‚‚‚Ag contacts of 2.9501(8) and 2.9732(9) Å, which are values close to the Ag-Ag distance in metallic silver, 2.89 Å, or in many silver(I) oxides.20 The analogous complex of Cu was unfortunately too unstable to provide suitable single crystals for an X-ray structure determination. Theoretical Calculations. The short distances observed for the Ag and Au derivatives indicate a feasible M‚‚‚M interaction of great theoretical interest. The size of the molecule under (19) Di Bernardo, P.; Tolazzi, M.; Zanonato, P. J. Chem. Soc., Dalton Trans. 1995, 1349. (20) Jansen, M. Angew. Chem., Int. Ed. Engl. 1987, 26, 1098.
(21) Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Gill, P. M. W.; Johnson, B. G.; Robb, M. A.; Cheeseman, J. R.; Keith, T. A.; Petersson, G. A.; Montgomery, J. A.; Raghavachari, K.; Al-Laham, M. A.; Zakrzewski, V. G.; Ortiz, J. V.; Foresman, J. B.; Cioslowski, J.; Stefanov, B.; Nanayakkara, A.; Challacombe, M.; Peng, C. Y.; Ayala, P. Y.; Chen, W.; Wong, M. W.; Andres, J. L.; Replogle, E. S.; Gomperts, R.; Martin, R. L.; Fox, D. J.; Binkley, J. S.; Defrees, D. J.; Baker, J.; Stewart, J. P.; Head-Gordon, M.; Gonzalez, C.; Pople, J. A. Gaussian 94, Revision C.3; Gaussian, Inc.: Pittsburgh, PA, 1995. (22) Møller, C.; Plesset, M. S. Phys. ReV. 1934, 46, 618. Hehre, W. J.; Radom, L.; Schleyer, P. v. R.; Pople, J. A. Ab Initio Molecular Orbital Theory; J. Wiley: New York, 1986. (23) Schlegel, H. B. J. Comput. Chem. 1982, 3, 214. (24) Hariharan, P. C.; Pople, J. A. Theor. Chim. Acta 1973, 28, 213. (25) Hehre, W. J.; Ditchfield, R.; Pople, J. A. J. Chem. Phys. 1972, 56, 2257. (26) Hay, P. J.; Wadt, W. R. J. Chem. Phys. 1985, 82, 299. (27) Frenking, G.; Antes, I.; Bo¨hme, M.; Dapprich, S.; Ehlers, A. W.; Jonas, V.; Neuhaus, A.; Otto, M.; Stegmann, R.; Veldkamp, A.; Vyboishchikov, S. F. In ReViews in Computational Chemistry; Lipkowitz, K. B., Boyd, D. B., Eds.; VCH: New York, 1996; Vol. 8. (28) Wark, T. A.; Stephan, D. W. Inorg. Chem. 1987, 26, 363.
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Figure 4. HF/II//HF/II absolute energies [hartrees] and optimized structural parameters [Å, deg] calculated for [M2(H2PCH2SH)2]2+.
Figure 5. MP2/II//MP2/II absolute energies [hartrees] and optimized structural parameters [Å, deg] calculated for [M2(H2PCH2SH)2]2+.
interatomic distances (3.612, 4.017, and 3.345 Å for Cu, Ag, and Au, respectively) are far removed from the experimental values (2.950 and 2.973 for Ag and 2.902 Å for Au). In contrast, the experimental radii observed for two- and fourcoordinate M(I) compounds9 suggest that the calculated AuAu distance should be intermediate between that of Cu-Cu and Ag-Ag when no interaction is present. However, the relatively short distance obtained at the HF/II level for the gold complex indicates an attraction that should be inherently relativistic since correlation is not included at the Hartree-Fock level. The same conclusion can be derived from the P-M-S angle (167.8, 160.4, and 174.9° for Cu, Ag, and Au, respectively). The correlation was accounted for at the MP2/II level. Figure 5 shows the absolute energies and the most relevant geometrical parameters of the [CH2(SHMPH2)2CH2]2+ optimized structures at this level. As can be observed, the calculated metal-metal interatomic distances are reduced to 3.089, 3.200, and 3.030 Å for Cu, Ag, and Au, respectively, which indicates that correlation effects are attractive in all coinage metals and that MP2 captures most of the physics of the CuI‚‚‚CuI and AgI‚‚‚AgI attraction. The Au-Au distance is still slightly shorter than Cu-Cu, which confirms the presence of both relativistic and correlation effects in the gold dimer. As expected from their experimental radii,9 the M-M distance is larger for silver than for copper or gold. The role of the correlation may also be deduced by the dramatic reduction of the P-M-S angle (from inner 167.8° to outer 179.7°, from 160.4° to 174.3°, and from inner 174.9° to outer 176.5° for Cu, Ag, and Au, respectively). In summary, our calculations indicate that metallophilic attraction is indeed present for all the coinage metals as a correlation effect and that it is strengthened by the relativistic effect for gold. Since theoretically predicted geometries are in close agreement with the experimental ones, we can assume that our calculations are accurate enough to obtain valid conclusions.
Experimental Section Instrumentation. Infrared spectra were recorded in the range 4000-200 cm-1 on a Perkin-Elmer 883 spectrophotometer and on a Perkin-Elmer FT-IR Spectrum 1000 spectrophotometer using Nujol mulls between polyethylene sheets. C, H, and S analyses were carried out with a Perkin-Elmer 240C microanalyzer. Mass spectra were recorded on a VG Autospec using the LSIMS techniques and nitrobenzyl alcohol as matrix and on a HP59987 A Electrospray. 1H, 19F, and 31P NMR spectra were recorded on a Bruker ARX 300 in CDCl and 3 (CD3)2CO solutions. Chemical shifts are quoted relative to SiMe4 (1H, external), CFCl3 (19F, external), and H3PO4 (85%) (31P, external). Solvent and Reagent Pretreatment. Dichloromethane and hexane were distilled from CaH2 and diethyl ether from sodium, under nitrogen atmosphere. [Cu(CH3CN)4]CF3SO3 was prepared as described28 using triflic acid instead of tetrafluoroboric acid or perchloric acid; [AuCl(tht)]29 and PPh2CH2SPh30 were prepared by reported literature methods. Caution! Perchlorate salts with organic cations may be explosiVe. Synthetic Procedures. Preparation of [Cu2(PPh2CH2SPh)2](CF3SO3)2 (1). To a solution of [Cu(CH3CN)4]CF3SO3 (0.122 g, 0.32 mmol) in CH2Cl2 (20 mL) was added PPh2CH2SPh (0.100 g, 0.32 mmol). The reaction mixture was stirred for 1 h at room temperature, and then the solvent was removed by reduced pressure to leave 1 as a white solid. Yield: 90%. Mass spectra: [CuPPh2CH2SPh]+ at m/z 371 (100%); [M + CF3SO3]+ at m/z 893 (7%). Anal. Calcd for C40H34Cu2F6O6P2S4, 1: C, 46.1; H, 3.3: S, 12.3. Found: C, 45.8; H, 3.2; S, 11.8. 31P{1H} NMR (CDCl3), δ: -8.7 (s). 19F NMR (CDCl3), δ: -77.97 (s). 1H NMR (CDCl3), δ: 7.62-7.19 (m, 30H, Ph), 3.99 (m, 4H, CH2). Preparation of [Ag2(PPh2CH2SPh)2](X)2 (X ) ClO4 (2a), CF3SO3 (2b)). PPh2CH2SPh (0.100 g, 0.32 mmol) was added to a solution of AgClO4 (0.067 g, 0.32 mmol of 2a) or AgCF3SO3 (0.083 g, 0.32 mmol of 2b) in 20 mL of Et2O. After stirring for 1 h a white precipitate of 2a or 2b was filtered off. Yield: 83% 2a, 70% 2b. Mass spectra: [AgPPh2CH2SPh]+ at m/z 417 (100%, 2a, 2b); [M + ClO4]+ at m/z 930 (6%, 2a); [M + CF3SO3]+ at m/z 981 (15%, 2b). Anal. Calcd (29) Allen, E. A.; Wilkinson, W. Spectrochim. Acta 1972, 28a, 2257. (30) Gerdau, T.; Kramolowsky, R. Z. Naturforsch. 1982, 37B, 332.
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Table 3. Details of Data Collection and Structure Refinement for Complexes 2a and 4 empirical formula crystal habit crystal size/mm crystal system space group a/Å b/Å c/Å R/deg β/deg γ/deg U/Å3 Z Dc/Mg m-3 M F(000) T/°C 2θmax/deg µ(Mo KR)/mm-1 transmission no. of reflcns measd no. of unique reflcns Rint R (F, F > 4σ(F))a wR (F2, all reflcns)b no. of reflcns used no. of params no. of restraints Sc max. ∆Fe Å-3
2a
4
C38H34Ag2Cl2O8P2S2 colorless prism 0.75 × 0.50 × 0.40 monoclinic P21/n 16.801(3) 15.618(4) 16.994(4) 90 119.08(2) 90 3897.0(15) 4 1.758 1031.36 2064 -130 50 1.383 0.839-0.956 9549 6876 0.0215 0.0391 0.0959 6876 487 0 1.054 1.781
C40H34Au2F6O3P2S4 colorless prism 0.30 × 0.30 × 0.20 triclinic P1h 9.5174(14) 10.2427(8) 11.8853(14) 79.785(8) 75.068(10) 80.246(8) 1092.4(2) 1 1.917 1260.79 604 -100 50 7.034 0.784-0.963 4081 3832 0.0139 0.0233 0.0534 3832 271 204 0.991 0.792
a R(F) ) ∑||F | - |F ||/∑|F |. b wR(F2) ) [∑{w(F 2 - F 2)2}/ o c o o c ∑{w(Fo2)2}]0.5; w-1 ) σ2(Fo2) + (aP)2 + bP, where P ) [Fo2 + 2Fc2]/ 3 and a and b are constants adjusted by the program. c S ) [∑{w(Fo2 - Fc2)2}/(n - p)]0.5, where n is the number of data and p the number of parameters.
for C38H34Ag2Cl2O8P2S2, 2a: C, 44.2; H, 3.3: S, 6.2. Found: C, 43.9; H, 3.3; S, 5.9. Calcd for C40H34Ag2F6O6P2S4, 2b: C, 42.5; H, 3.0: S, 11.3. Found: C, 42.1; H, 3.1; S, 11.6. 31P{1H} NMR {(CD3)2CO, -80 °C}, δ: 9.4 [d, br, Jav(AgP) ) 637 Hz] (2a); 9.2 [d, br, Jav(AgP) ) 625 Hz] (2b). 19F NMR (CDCl3), δ: -77.58 (2b). 1H NMR (CDCl3), δ: 7.70-7.25 (m, 30H, Ph), 4.34 (d, 4H, CH2) (2a); 7.717.00 (m, 30H, Ph), 4.16 (d, 4H, CH2) (2b). Preparation of [AuCl(PPh2CH2SPh)] (3). PPh2CH2SPh (0.100 g, 0.32 mmol) was added to a solution of [AuCl(tht)] (0.104 g, 0.32 mmol)
in 20 mL of CH2Cl2 and the reaction mixture was stirred for 1 h. The solvent was evaporated to ca. 5 mL, and addition of 20 mL of hexane gave 3 as a white solid. Yield: 70%. Mass spectra: [M - Cl]+ at m/z 505 (100%). Anal. Calcd for C19H17AuClPS, 3: C, 42.2; H, 3.2; S, 5.9. Found: C, 41.9; H, 2.7; S, 5.9. 31P{1H} NMR (CDCl3), δ: 27.1 (s). 1H NMR (CDCl3), δ: 7.72-7.03 (m, 15H, Ph), 3.83 (d, 2H, CH2). Preparation of [Au2(PPh2CH2SPh)2](CF3SO3)2 (4). To a solution of 3 (0.175 g, 0.32 mmol) in CH2Cl2 (20 mL) was added AgCF3SO3 (0.083 g, 0.32 mmol), and the mixture was stirred for 1 h. The AgCl was filtered off, and the solution was layered with hexane. Crystals of 4 were obtained within 3 days. Yield: 50%. Mass spectra: [AuPPh2CH2SPh]+ at m/z 505 (100%); [M + CF3SO3]+ at m/z 1159 (5%). Anal. Calcd for C40H34Au2F6O6P2S4, 4: C, 36.7; H, 2.6; S, 9.8. Found: C, 36.6; H, 2.4; S, 9.8. 31P{1H} NMR ((CD3)2CO), δ: 34.5 (s). 19F NMR ((CD3)2CO), δ: -77.98. 1H NMR ((CD3)2CO), δ: 8.107.52 (m, 30H, Ph), 5.58 (m, 4H, CH2). Crystal Structure Determinations. Crystals were mounted in inert oil on glass fibers. Data were collected using monochromated Mo KR radiation (λ ) 0.710 73 Å) on a Siemens P4 diffractometer (4) or a Stoe STADI-4 (2a), both with Siemens LT-2 low-temperature attachment (scan type ω or ω/θ). Cell constants were refined from setting angles of ca. 60 reflections in the 2θ range 7-25° (4) or (ω angles of 56 reflections in the 2θ range 20-23° (2a). Absorption corrections were applied on the basis of ψ scans. Structures were solved by the heavy atom method (4) or direct methods (2a) and refined anisotropically on F2 (program SHELXL-93).31 Hydrogen atoms were included using a riding model. To improve refinement stability, a range of restraints to local ring symmetry and light atom displacement parameters were employed for complex 4. Complex 2a showed a marked tendency to crystallize as interpenetrating twins; despite careful selection of the crystal using polarized light, the residual electron density is higher than expected for a silver compound and may be attributed to a small twin component. Further details are given in Table 3.
Acknowledgment. This work was supported by Spanish DGICYT (PB97-1010-CO2-02) and (PB94-0079), UR-Iberdrola (96PYD03EFG), and the Fonds der Chemischen Industrie. Supporting Information Available: X-ray crystallographic information about 2a and b in CIF format, is available (9 pages). Ordering information is given on any current masthead page. IC980786Q (31) Sheldrick, G. M. SHELXL-93: A program for crystal structure refinement; University of Go¨ttingen: Germany, 1993.
